Vibration damping device and bucket for construction machine

ABSTRACT

A bucket for a construction machine including a side plate ( 11 ); a bottom plate ( 12 ), at least a portion of which is connected to the side plate ( 11 ); and a laminated plate ( 20 ) that is attached to an outside of the side plate ( 11 ). At least a part ( 16 ) of the portion where the side plate ( 11 ) and the bottom plate ( 12 ) are connected on an inside of the side plate ( 11 ) and the bottom plate ( 12 ) is reinforced.

This is a divisional application of Ser. No. 12/071,525, filed Feb. 21,2008, which is a divisional application of Ser. No. 10/526,224, filedMar. 1, 2005, now U.S. Pat. No. 7,681,689, which is the National Stageof International Application No. PCT/JP2003/011181, filed Sep. 2, 2003.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a vibration damping device whichsuppresses vibration generated by a base material so that noise emittedfrom the base material is reduced, and a bucket for a constructionmachine.

2. Description of Related Art

In recent years, low noise levels have been required in constructionmachinery, especially in the case of nighttime work and in residentialareas, and legal noise regulations which restrict noise to fixed levelsor lower have also been enacted in various countries. For example, inthe case of hydraulic excavators equipped with work equipment includingbuckets, it has been confirmed by experiment that such buckets are themain source of noise. It has been claimed that approximately 80% of thenoise emitted from such work equipment is noise emitted from buckets.

Accordingly, attempts have been made to attach vibration dampingmaterials to buckets in order to suppress the vibration that isgenerated in the buckets, especially the side plates of the buckets, andthus reduce the noise that is emitted from these side plates. Vibrationdamping materials used in such cases have generally been materialscalled viscoelastic materials, such as rubber, resins, asphalt or thelike.

However, construction machinery is commonly used to perform work underharsh conditions, with the work equipment exposed to earth, sand and thelike, and if vibration damping materials consisting of viscoelasticmaterials are attached to the work equipment, the problem ofinsufficient durability arises. Furthermore, such viscoelastic materialsare generally constrained by metal plates, and in cases where thesemetal plates are repaired by welding, the problem of burning of theviscoelastic materials also arises. Since such viscoelastic materialsare expensive, the problem of high cost of noise countermeasures alsoarises.

Accordingly, in response to the demand for the development of a low-costvibration damping device which has a high durability and involves noburning during repair, the assignee of the present application hasalready developed a laminated plate and filed a patent application forthis plate, which has been disclosed in Japanese Patent ApplicationLaid-Open No. 2000-219168 (or U.S. Pat. No. 6,332,509), Japanese PatentApplication Laid-Open No. 2002-48188 and the like. With respect to theabovementioned publications, an explanation will be made with referenceto FIG. 2. A plurality of thin steel plates 21 (hereafter referred to as“thin plates 21”) are laminated on the side plate 11 of the bucket, thusforming laminated plate 20. It is indicated that relatively thick steelplate 30 (hereafter referred to as “protective plate 30”) that protectthe thin plates 21 is further superimposed on top of the laminated plate20, and that the periphery 20 a (see FIG. 1) is fastened by performingall round fillet welding or intermittent fillet welding, or byperforming intermittent plug welding, bolt fastening or the like. Sincethe laminated plate 20 is constructed from an inexpensive material thathas a high durability and is resistant to burning, i. e., steel, theproblem points encountered in conventional viscoelastic materials can besolved.

The mechanism whereby the laminated plate 20 suppresses the vibrationgenerated in the side plate 11 and thus reduces the noise emitted fromthe side plate 11 is described in the abovementioned publications; thismechanism will be described with reference to FIGS. 4A and 4B.Specifically, when the side plate 11 vibrates, this vibration istransmitted to the laminated plate 20, so that the thin plates 21, 21′constituting the laminated plate 20 undergo deformation. In thelaminated plate 20 in which numerous thin plates 21, 21′ aresuperimposed, the amount of deformation differs in each layer.Specifically, the respective curvature radii r1 and r2 differ inadjacent thin plates 21, 21′. Accordingly, in the thin plates 21, 21′ inwhich the original displacement was X (see FIG. 4A), the displacementrespectively varies to X+ΔX2 and X+ΔX1 as a result of the microscopicdisplacement caused by the vibration, so that a relative displacement ofΔX2−ΔX1 is generated between the two thin plates 21 and 21′. Thisrelative displacement of ΔX2−ΔX1 causes the generation of a frictionalforce (hereafter referred to as an “inter-layer frictional force”)between the thin plates 21 and 21′. The vibration energy generated inthe side plate 11 is converted into thermal energy by this inter-layerfrictional force. As a result, the vibration generated in the side plate11 is suppressed so that the noise emitted from the side plate 11 isreduced.

Accordingly, as is shown in FIG. 4B, the independent deformation of thethin plates 21 and 21′ so that a relative displacement of ΔX2−ΔX1 isgenerated is a condition for performing vibration damping. Conversely,therefore, if the two thin plates 21 and 21′ are fastened in place sothat these plates function as an integral unit, the independentdeformation is hindered, so that there is absolutely no generation of arelative displacement or very little generation of a relativedisplacement; as a result, no vibration damping effect is obtained, oran extremely small vibration damping effect is obtained.

This will be explained with reference to FIG. 1. In a conventionaldevice, the peripheries 20 a of the laminated plate 20 are fastened tothe side plate 11 by welding or the like. However, in a commonconventional structure, the interior parts (used in the sense of theportions other than the peripheries 20 a) of the laminated plate 20 arenot fastened to the side plate 11, so that the independent deformationof the respective layers is not impeded, thus producing a high vibrationdamping effect. However, it has become clear that the following problemsarise if the interior parts of the laminated plate 20 are not fastened.

First of all, gaps are generated between the thin plates 21 and 21′ thatconstitute the laminated plate 20, and gaps are generated between theside plate 11 and the laminated plate 20, by the thermal strain that isgenerated in the welding process during manufacture. As a result, thefrictional force that should inherently occur between the thin plates 21and 21′ during the vibration of the side plate 11 either does not occuror occurs to only a very slight extent, so that a vibration dampingeffect is either completely absent or present to a very slight extent.

Secondly, during actual work performed by construction machinery,excessively large external forces are commonly applied to the side plate11 as a result of the bucket striking rocks and the like. Consequently,the laminated plate 20 in which the internal portions are not fastenedand only the peripheries 20 a are fastened is easily caused to “floatupward” by these excessive external forces. In other words, thelaminated plate 20 separates from the side plate 11, and the thin plates21 and 21′ separate from each other. As a result, the inter-layerfrictional force that should be generated between the thin plates 21 and21′ during the vibration of the side plate 11 is either not generated atall or generated only to a very slight extent, so that a vibrationdamping effect is either not obtained at all or obtained only to a veryslight extent.

Thus, in order to obtain a high vibration damping effect, it isdesirable that the internal portions of the laminated plate 20 not befastened, so that the deformation of the thin plates 21 is not impeded.However, if the internal portions of the laminated plate 20 are notfastened, “floating” occurs as a result of thermal strain during themanufacture of the bucket and external forces during the use of thebucket, so that the problem of a loss of the vibration damping effectarises.

Furthermore, the types of buckets used in construction machinery varywidely according to the size, specifications and working applications ofthe construction machinery. When the present inventors performedexperiments on various types of buckets with different sizes, shapes,dimensions and the like, and confirmed the effect obtained by attachinglaminated plate to the side plate, the inventors discovered that theeffect varies according to the type of bucket involved. Specifically,depending on the type of bucket involved, there are cases in which thecontribution of the side plate to noise is large, and cases in which thecontribution of the side plate to noise is small and the contribution ofthe bottom plate to noise is large. The following countermeasures areconceivable in such cases.

(1) The contribution to noise is measured for various types of buckets,and in the case of buckets in which the contribution of the bottom plateto noise is large, noise countermeasures are taken with respect to thebottom plate as well.

(2) Noise countermeasures are uniformly taken in the bottom plate forall types of buckets.

However, in cases where the method of the abovementioned (1) is adopted,noise experiments and the like must be performed each time that a bucketis newly designed, which involves considerable trouble. Furthermore, incases where the method of the abovementioned (2) is adopted, it isnecessary to add parts used for noise countermeasures even in the caseof buckets that do not require noise countermeasures, so that the costis increased.

Accordingly, it is desirable to set clear standards for the requirementof noise countermeasures with respect to the bottom plate, and toperform noise countermeasures using the minimum required effort for theminimum required buckets among the various types of buckets, withoutperforming noise experiments or the like. On the other hand, in caseswhere noise counter measures are performed on the bottom plates ofbuckets, there are instances in which laminated plate cannot be attached(unlike the case of the side plate). Specifically, during the workperformed by construction machinery, the bottom plate of the bucketoften has occasion to strike rocks or the like; accordingly, compared tothe side plate, the bottom plate is more frequently subjected toexcessive external forces, so that the bottom plate is subjected tosevere wear. Accordingly, there is a danger that the laminated plateattached to the bottom plate will be destroyed or separated, and istherefore deficient in durability. Furthermore, in cases where laminatedplate is attached to the bottom plate, the problem of increased costalso arises.

Therefore, in order to avoid such problems, it is conceivable thatvibration damping might be performed while increasing the rigidity ofthe bottom plate by reinforcing the bottom plate with a reinforcingmaterial. Depending on the type of bucket involved, there may be bucketsin which reinforcing members with a large thickness (called wear plates)are attached to the portions of the side plate of the bucket that areclose to the bottom plate, and it is conceivable that vibration dampingof the bottom plate might be performed by increasing the thickness ofsuch wear plate. However, increasing the thickness of the wear plateleads to an increase in the weight of the bucket, and thus has adeleterious effect on the performance of the construction machinery.Specifically, when the weight of the bucket is increased, the inertialmoment of the work equipment increases, so that it is necessary toincrease the counter-weight by a corresponding amount. When thecounter-weight is increased, the problem of an increase in the turningradius of the construction machinery arises. Accordingly, it isdesirable that reinforcement of the bottom plate of the bucket beperformed with the minimum necessary increase in weight.

Furthermore, a vibration damping device using a laminated plate in whicha plurality of plates are partially coupled is known as a vibrationdamping device which has an effect on noise reduction in the machinery,and which is compact and superior in terms of durability. Furthermore,bolt fastening, plug welding or complete-periphery welding is used assuch partial coupling (for example, see the abovementioned JapanesePatent Application Laid-Open No. 2002-48188, pages 3 through 5, andFIGS. 1 through 8). In vibration damping devices using the laminatedplate since the laminated plate is partially coupled to the noisegenerating parts (vibrating parts), very small positional deviations orgaps are generated between the vibrating parts and laminated plate andbetween the plates that make up the laminated plate when the noisegenerating parts vibrate. Since these very small positional deviationsand gaps successively arise while constantly varying, friction andimpacts between the plates are repeated. Accordingly, the vibrationalenergy of the noise generating parts is converted into thermal energy bythe friction and impacts, and is diffused, so that the vibration can bereduced, thus reducing the noise.

However, in the case of such conventional techniques, problems such asthose described below arise. Specifically, in cases where suchtechniques are applied to the side plate of the bucket in a hydraulicexcavator, if bolt fastening or plug welding is used for the partialcoupling of the side plate and laminated plate, rain water enters viathe end surfaces of the laminated plate so that rusting occurs betweenthe plates, thus causing a drop in the vibration damping performance. Ifall round welding of the end surfaces of the laminated plate is used forthe partial coupling of the side plate and laminated plate in order toprevent rusting, the plates forming the laminated plate are mutuallyconstrained, so that the generation of very small positional deviationsand the like is impeded, thus causing a drop in the vibration dampingperformance.

The application of laminated plate such as shown in FIG. 29 to the sideplates of the bucket is conceivable as one example of a technique thatcan protect the welded parts of the laminated plate. In the bucket 101,side plates 103, 103 are respectively welded to both sides of a bottomplate 102 which is bent into substantially a C shape. Furthermore, edgeplates 104, 104 and 105 are respectively welded to the side plates 103,103 and bottom plate 102 to form the opening part of the bucket 101. Aplurality of teeth 106 are mounted on the edge plate 105. Pin bosses 107which are connected to the work equipment of the hydraulic excavator aredisposed on the end part located on the opposite side from the toothattachment part of the bottom plate 102. Wear plate 108 is disposed onthe peripheral parts of the outside surfaces of the side plate 103 sothat the wear plate 108 runs along the bottom plate 102. Laminated plate150 is bonded to the outside surfaces of the side plate 103 so that thelaminated plate 150 is surrounded by the edge plate 104 and wear plate108. As is shown in FIG. 30, the laminated plate 150 comprises an innerplate 151 consisting of a specified number of laminated thin steelplates, and an outer plate 152 with a specified thickness which islaminated on the outside of the inner plate 151, and which retains andprotects the inner plate 151. These plates are bonded to the side plate103 so that the side plate 103, inner plate 151 and outer plate 152 showsubstantially tight adhesion to each other. A gap d1 is formed betweenthe laminated plate 150 and the wear plate 108 as welding margins forthe welding of the laminated plate 150 and wear plate 108 to the sideplate 103. Furthermore, as is shown in FIG. 31, a gap d2 is formedbetween the laminated plate 150 and the edge plate 104 as weldingmargins for the welding of the laminated plate 150 and edge plate 104 tothe side plate 103. For example, as is shown in FIGS. 32A and 32B, bothgaps d1 and d2 are embedded by repeating fillet welds twice.Specifically, laminated plate 150 is bonded to the side surface of thebucket 101 by all round welding.

As a result of the abovementioned construction, noise during excavationwork can be reduced by the dissipation of vibrational energy by theinner plate 151 of the laminated plate 150 as thermal energy.Furthermore, the laminated plate 150 disposed on the side surfaces ofthe bucket 101 prevents the entry of rain water into the interior partsof the laminated plate as a result of the all round welding, and thusprevents the occurrence of rusting between the plates, so that thevibration damping performance can be maintained. Moreover, the edgeplate 104 and wear plate 108 protect these welded parts from friction orimpact with rocks and the like during excavation work; accordingly, wearand damage of the welded parts of the laminated plate 150 can beprevented, so that the durability of the laminated plate 150 can beimproved.

However, the following problems are encountered even in cases where theabovementioned wear plate 108 is used.

(1) The laminated plate that converts the vibrational energy intothermal energy arising from friction between the plates, and thusdissipates this energy, shows an improved vibration damping performanceas the number of points of constraint is reduced. However, the innerplate 151 of the laminated plate 150 is constrained around the entireperiphery by all round welding of the periphery, so that the vibrationdamping performance drops. Conversely, in cases where the peripheries ofthe laminated plate 150 are intermittently welded in order to reduce thenumber of points of constraint and improve the vibration dampingperformance, rusting occurs as a result of the invasion of the interiorparts by rain water.

(2) If specified gap d1 is not ensured between the laminated plate 150and the wear plate 108 during manufacture, a sufficient welding qualitycannot be obtained. Considerable work is required in order to positionthe inner plate 151 and outer plate 152 so that the gap d1 is ensured;as a result, the cost is increased.

(3) Since the volume of the welded parts is large, the cost increaseswith the amount of work that is required. Conversely, if the peripheriesof the laminated plate 150 are intermittently welded in order to reducethe amount of welding, rusting occurs as a result of the invasion of theinterior parts by rain water as in the case of the abovementioned (1).

(4) In order to prevent floating and deformation caused by thermalstrain during continuous welding, it is necessary to effect a temporaryattachment of the laminated plate 150 and side plate 103 at an extremelylarge number of points, so that considerable work is required, and thecost is increased.

Furthermore, as an example of another application in which laminatedplate is bonded, there is an application in which laminated plate 160(comprising a specified number of inner plates 161 and an outer plate162) is bonded to the inclined plate 172 of the hopper 171 of a crusher170 as shown (for example) in FIG. 33. In this case, it is conceivablethat all round welding might be used in order to prevent foreign mattersuch as water or the like from invading the interior parts of thelaminated plate. In this case as well, since the entire periphery ofeach of the inner plates 161 of the laminated plate 160 is constrainedby all round welding as in the abovementioned (1), the vibration dampingperformance drops. Conversely, if the peripheries of the laminated plate160 are intermittently welded in order to improve the vibration dampingperformance, rusting occurs as a result of the invasion of the interiorparts by water and the like.

SUMMARY OF THE INVENTION

The present invention was devised in order to solve such problemsencountered in the prior art; it is an object of the present inventionto provide a vibration damping device in which a high vibration dampingeffect can be maintained by fastening appropriate parts in the interiorpart of the laminated plate so that there is no loss of the vibrationdamping effect due to thermal strain during manufacture or theoccurrence of “floating” caused by external forces during use, and sothat there is no interference with the independent deformation of thethin plates that make up the laminated plate. Furthermore, it is anobject of the present invention to provide a bucket for a constructionmachine which is devised so that noise countermeasures can be taken withthe minimum required effort, without performing noise experiments or thelike on the bucket, and which makes it possible to reinforce the bottomplate of the bucket with the minimum required increase in weight.Moreover, it is an object of the present invention to provide avibration damping device which is superior in terms of vibration dampingperformance, and which can prevent the generation of noise in theinternal portions.

In order to achieve the abovementioned object, the first aspect of avibration damping device of the present invention is a vibration dampingdevice comprising a laminated plate in which at least an interior partthereof is fastened to a base material that emits noise, characterizedin that the interior part is a part other than a part that forms a loopof a vibration mode when the base material is caused to vibrate in thevibration mode at a specified frequency.

Below, some of the effects and merits of the present invention will bedescribed with reference to the attached figures and reference symbolsin the figures in order to facilitate understanding However, theattached figures and reference symbols in the figures merely indicateexamples, and do not limit the present invention. In the abovementionedfirst construction, as is shown in FIG. 3, when the laminated plate 20is fastened to the base material 11, a part G other than a part E thatforms a loop of the vibration mode 1 at a specified frequency when thebase material 11 is caused to vibrate in this vibration mode 1 isfastened.

When the amplitude distribution of the vibration is taken in a casewhere the base material 11 is caused to vibrate in the vibration mode 1at a specified frequency, the size of the amplitude varies according tothe part even in the case of the same structure, as is shown in FIG. 5A.Specifically, there is a part (PH in FIG. 5A) where the amplitude islarge, i. e., the part that forms a loop of the vibration mode 1, and apart (PL in FIG. 5A) where the amplitude is small, i.e., the part thatforms a node of the vibration mode 1. In the part where the amplitude islarge, the amount of deformation of the thin plates 21, 21′ that formthe laminated plate 20 is also large, and the frictional force betweenlayers is also large.

Here, if the laminated plate 20 is fastened to the base material 11 inthe part E that forms the loop of the vibration mode 1, the independentdeformation of the thin plates 21, 21′ that make up the laminated plate20 is impeded, so that the inter-layer frictional force is eithercompletely eliminated or else is extremely small. Consequently, avibration damping effect arising from the laminated plate 20 is eithernot obtained at all, or else is obtained only to a very slight extent.Accordingly, the laminated plate 20 is fastened to the base material 11in the part other than the part E that forms the loop of the vibrationmode 1; in concrete terms, the laminated plate 20 is fastened in thepart G that forms the node of the vibration mode 1.

The part G that forms the node of the vibration mode 1 is inherently apart where the deformation of the thin plates 21, 21′ that make up thelaminated plate 20 is either small or almost non-existent. Accordingly,even if fastening is performed in this part, the vibration dampingeffect that is lost is either extremely small or almost non-existent.Consequently, the deleterious effect on the vibration damping effectcaused by the fastening of the laminated plate 20 can be suppressed to aminimum. Thus, in the first construction, since the construction isdevised so that the optimal part G in the interior parts of thelaminated plate 20 is fastened, there is no loss of the vibrationdamping effect due to thermal strain during manufacture or theoccurrence of “floating” caused by external forces during use.Furthermore, the independent deformation of the thin plates 21 that makeup the laminated plate 20 is not impeded, so that a high vibrationdamping effect can be maintained.

The second aspect of a vibration damping device is a vibration dampingdevice comprising a laminated plate in which at least an interior partthereof is fastened to a base material that emits noise, characterizedin that the interior part is a part other than a part that forms a loopwith respect to a plurality of vibration modes when the base material iscaused to vibrate in respective vibration modes at a plurality offrequencies.

In this second construction, as is shown in FIGS. 5A through 5D, whenthe base material 11 is fastened to the laminated plate 20, the part Gin the internal part other than the part that forms a loop with respectto a plurality of vibration modes 1, 2, 3 and 4 when the base material11 is caused to vibrate in the respective vibration modes 1, 2, 3 and 4with different frequencies is fastened. Since the device is devised sothat the part G where the deformation of the thin plates 21, 21′ thatmake up the laminated plate 20 is either small or almost non-existentwith respect to the respective vibrations modes 1, 2, 3 and 4 at aplurality of frequencies is fastened, the deleterious effect on thevibration damping effect caused by the fastening of the laminated plate20 over a plurality of frequencies can be suppressed to a minimum, sothat noise caused by the mixing of a plurality of frequency componentscan be reduced.

The third aspect of a vibration damping device is a vibration dampingdevice comprising a laminated plate in which at least an interior partthereof is fastened to a side plate of a bucket of a constructionmachine, characterized in that the interior part is within a region Gcomprising i) a part D consisting of a center point d of a line segmentBC that connects a point B where a line segment CA that connects acircular arc center C of the side plate which has a substantiallycircular arc shape in at least a portion of one side and a point A wherethere is a transition from the substantially circular arc shape toanother shape on a side of attachment of the bucket to the constructionmachine intersects with the laminated plate, and the circular arc centerC, and an area in the vicinity of the center point d, ii) a part Fconsisting of a center point f of the line segment CA and an area in thevicinity of the center points f, and iii) a region between the part Dand part F.

Specifically, as is shown in FIGS. 5A through 5D, it has been confirmedthat when the side plate 11 is caused to vibrate in respective vibrationmodes 1, 2, 3 and 4 at a plurality of frequencies, the parts other thanthe loop of the vibration modes for all of the frequencies are in theregion G, as shown in FIG. 1. Here, the side plate 11 is one concreteexample of the base material 11. In this third construction, if (forexample) the part D within the region G is fastened, the deleteriouseffect on the vibration damping effect caused by the fastening of thelaminated plate 20 can be suppressed to a minimum.

The first aspect of a bucket for a construction machine of the presentinvention is a bucket for a construction machine comprising a sideplate, a bottom plate, at least a portion of which is connected to theside plate, and a laminated plate which is attached to the side plate,characterized in that in cases where a ratio Wp/Hs of a width Wp of abottom plate to a height Hs of the side plate is 1.47 or greater, atleast a part of the portion where the side plate and bottom plate areconnected is reinforced.

In this first bucket construction, the standard for the requirement ofnoise countermeasures in the bottom plate is clearly defined as “theratio Wp/Hs of the width Wp of the bottom plate to the height Hs of theside plate being 1.47 or greater”, and the bottom plate is reinforcedaccording to this standard. As a result, noise countermeasures can betaken with the minimum required effort only in the case of buckets thatrequire noise countermeasures (among the various types of buckets),without performing noise experiments or the like.

The second aspect of a bucket for a construction machine is a bucket fora construction machine comprising a side plate, a bottom plate, at leasta portion of which is connected to the side plate, and a laminated platewhich is attached to the outside of the side plate, characterized inthat in cases where a ratio Wp/Hs of a width Wp of the bottom plate to aheight Hs of the side plate is 1.47 or greater, a part, which forms aloop of a vibration mode, of the potion where the side plate and bottomplate are connected is reinforced.

In this second bucket construction, as in the abovementioned firstbucket construction, the construction is devised so that the bottomplate is reinforced according to a standard indicating the need toreinforce the bottom plate; accordingly, noise countermeasures can beperformed using the minimum required effort. Furthermore, since theconstruction is devised so that the part that forms the loop of thevibration mode (among the respective parts where the side plate andbottom plate are connected) is reinforced, the minimum necessaryreinforcement of the bottom plate can be performed, so that thedeleterious effect on the performance of the construction machine can besuppressed to a minimum.

The third aspect of a bucket for a construction machine is a bucket fora construction machine comprising a side plate, a bottom plate, at leasta portion of which is connected to the side plate, and a laminated platewhich is attached to the side plate, characterized in that in caseswhere a ratio Wp/Hs of a width Wp of the bottom plate to a height Hs ofthe side plate is 1.47 or greater, a connecting member that connects theside plate and bottom plate is provided so that a ratio Wp′/Hs of asubstantial width Wp′ of the bottom plate to the height Hs is less than1.47.

In this third bucket construction, as in the case of the abovementionedfirst bucket construction, noise countermeasures can be performed withthe minimum required effort. Furthermore, the noise emitted from thebottom plate is reduced by attaching connecting members so that theratio Wp′/Hs is less than 1.47. In addition, since the construction isdevised so that the noise emitted from the side plate is reduced byattaching the laminated plate in a state in which the ratio Wp′/Hs isless than 1.47, the noise emitted from the bucket can be maximallyreduced in the most efficient manner.

The fourth aspect of a bucket for a construction machine is a bucket fora construction machine comprising a side plate, a bottom plate, at leasta portion of which is connected to the side plate, and a laminated platewhich is attached to the side plate, characterized in that at least apart of the portion where the side plate and bottom plate are connectedon insides of the side plate and bottom plate is reinforced.

In this fourth construction, since the noise emitted from the bottomplate is reduced, not only the noise from the sides of the bucket butalso the noise from the front of the bucket is reduced. Furthermore, asa result of the increased rigidity of the bucket as a whole, the noisefrom the sides is reduced to a greater extent than before reinforcement.Moreover, since only the inside connected parts of the bucket arereinforced, the weight increase caused by the reinforcing material issmaller than in cases where a reinforcing member such as a wear plate isdisposed on the outside of the bucket.

The fourth aspect of a vibration damping device is a vibration dampingdevice comprising a laminated plate formed by laminating a specifiednumber of inner plates and an outer plate that is disposed on theoutside of the specified number of inner plates, characterized in thatthe specified number of inner plates are tightly sealed by the outerplate and a machine that is the object of vibration damping.

Preferably, furthermore, this is a vibration damping device comprising alaminated plate formed by laminating a specified number of inner plates,and an outer plate which is disposed on outsides of the specified numberof inner plates and which has a shape that differs from those of theinner plates, the inner plates are caused to contact members of themachine that is the object of vibration damping, and the laminated plateis coupled to the members of the machine by performing continuouswelding on the peripheral edges of the outer plate. In thisconstruction, the invasion of rain water is prevented by performingcontinuous welding (all round welding) of the outer plate of thelaminated plate so that the occurrence of rusting between the plates canbe prevented.

The vibration damping device may also be devised so that when thelaminated plate is coupled to members of the machine, intermittentwelding consisting of welding in a plurality of locations is performedon the peripheral edges of the inner plates. In this construction, sincethe degree of constraint of the inner plates is lowered by usingintermittent welding on the peripheral edges of the inner plates,superior vibration damping characteristics can be obtained, and avibration damping device which has a conspicuous noise reducing effectcan be obtained.

The vibration damping device may also be devised so that the member ofthe machine has a contact member that is capable of contacting the endportions of the laminated plate, the inner plate has a contact part thatprotrudes beyond a peripheral edge of the outer plate and contacts withthe contact member, and continuous welding that covers the contact partof the inner plate is performed between the peripheral edges of theouter plate and the contact member. In this construction, the specifiednumber of inner plates can easily be positioned by causing the contactparts of the inner plates to contact the contact members on the machineside. Furthermore, temporary fastening for the purpose of preventingfloating and deformation caused by thermal strain during continuouswelding becomes unnecessary, so that the manufacturing work and cost canbe reduced. Moreover, since the contact members on the machine sideprotect the welded parts of the laminated plate, damage or wear of thewelded parts caused by collision or friction with foreign matter can beprevented, so that the durability of the laminated plate can beimproved.

The vibration damping device may also be devised so that a plurality ofprotruding parts that match a peripheral edge shape of the outer plateare disposed on the peripheral edge of the inner plate, and theplurality of protruding parts of the inner plate are intermittentlywelded by performing continuous welding on the peripheral edge of theouter plate. In this construction, the protruding parts of the innerplates are welded by the continuous welding process of the outer plateso that intermittent welds can be formed. Accordingly, the manufacturingprocess is simple and inexpensive. Furthermore, since the protrudingparts of the inner plates substantially match the peripheral edge shapeof the outer plate, these parts can be used for the positioning of therespective plates of the laminated plate so that the positioning work ofthe respective inner plates and outer plate is easy, and a low-costvibration damping device can be obtained.

The vibration damping device may also be devised so that a length of thecontact parts of the inner plates is 100 to 280 mm. In thisconstruction, since the intermittent welding pitch of the peripheraledges of the inner plates is set at 100 to 280 mm on the basis of testresults, an extremely superior noise reduction effect can be obtained.

The vibration damping device may also be devised so that the pluralityof protruding parts of the inner plates are disposed at intervals of 100to 280 mm. In this construction, since the intermittent welding pitch ofthe peripheral edges of the inner plates is set at 100 to 280 mm on thebasis of test results, an extremely superior noise reduction effect canbe obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a bucket showing the bucket side plate in afirst embodiment of the present invention;

FIG. 2 is a diagram showing a sectional view of the side plate of thebucket shown in FIG. 1;

FIG. 3 is a diagram showing the amount of deformation of the laminatedplate according to a loop and a node of the vibration mode in order toillustrate the first embodiment;

FIGS. 4A and 4B are explanatory diagrams of the deformation of the thinplate in the first embodiment, with FIG. 4A showing the case ofnon-vibration of the side plate and FIG. 4B showing the case ofvibration of the side plate;

FIGS. 5A through 5D are distribution diagrams showing the size of theamplitude when the side plate in the first embodiment is caused tovibrate in respective vibration modes (PL (in the figures) indicating “anode”, PH indicating “a loop”, and PM indicating “an intermediate area”(which is not the node but which has a small amplitude)), with FIG. 5Ashowing the vibration mode 1, FIG. 5B showing the vibration mode 2, FIG.5C showing the vibration mode 3, and FIG. 5D showing the vibration mode4;

FIG. 6 is a perspective view of a bucket constituting a secondembodiment of the present invention;

FIG. 7 is an explanatory diagram corresponding to a sectional view 7-7in FIG. 6, showing dimensions of respective parts of the bucket;

FIGS. 8A and 8B show the bucket with connecting members attached in thesecond embodiment, with FIG. 8A corresponding to a sectional view 8A-8Ain FIG. 6, and FIG. 8B being a perspective view of the inside of thebucket;

FIG. 9 is a diagram showing the relationship between the ratio of thewidth of the bottom plate to the height of the side plate and thecontribution to noise in the second embodiment;

FIG. 10 is a distribution diagram of the size of the amplitude when thebucket is caused to vibrate in a vibration mode at a specified frequencyin the second embodiment;

FIGS. 11A and 11B show how a hydraulic excavator equipped with a bucketperforms loading work into a truck in an example of the secondembodiment, with FIG. 11A being an explanatory side view, and FIG. 11Bbeing an explanatory plan view;

FIG. 12 is a perspective view of a bucket constituting a thirdembodiment of the present invention;

FIG. 13 is a side view of the bucket of the third embodiment;

FIG. 14 is a perspective view of the laminated plate in the thirdembodiment;

FIG. 15A is a sectional view of essential parts corresponding to thesection 15A-15A in FIG. 13;

FIG. 15B is a sectional view of essential parts corresponding to thesection 15B-15B in FIG. 13;

FIGS. 16A, 16B and 16C are sectional views of essential parts showingthe welded state in the third embodiment, with FIG. 16A showing a casein which intermittent welding is performed in the gap shown in FIG. 15A,FIG. 16B showing a case in which continuous welding is performed in thegap shown in FIG. 15A, and FIG. 16C showing a case in which continuouswelding is performed in the gap shown in FIG. 15B;

FIG. 17 shows measured data regarding the relationship between thewelding pitch of the inner plates and the generated noise level in thethird embodiment;

FIG. 18 is an explanatory diagram of the welding pitch in the thirdembodiment;

FIG. 19A is another example of the third embodiment;

FIG. 19B is a sectional view along line 19B-19B in FIG. 19A;

FIG. 20 is a side view of a mobile crusher constituting a fourthembodiment of the present invention;

FIG. 21 is a perspective view of the hopper in the fourth embodiment;

FIG. 22 is a plan view of the inclined walls in the fourth embodiment;

FIG. 23A is a sectional view along line 23A-23A in FIG. 22;

FIG. 23B is a sectional view along line 23B-23B in FIG. 22;

FIG. 24 is an explanatory diagram of the welding pitch in the fourthembodiment;

FIGS. 25A through 28 are plan views of other aspects of the laminatedplate constituting modifications of the third and fourth embodiments,with FIG. 25A showing an example in which the cut-out parts have a waveshape, FIG. 25B showing an example in which a plurality of holes usedfor plug welding are formed in the peripheral edges of the inner plates,FIG. 25C showing an example in which a plurality of holes for welding tothe side plate are formed in the inner plates and outer plate, FIG. 26showing an example in which end parts of the inner plates on the edgeplate side are caused to protrude beyond the peripheral edges of theouter plate, and cut-out parts are formed in the protruding parts, FIG.27 showing an example in which a plurality of protruding parts andcut-out parts are formed in the end parts of the inner plates on theedge plate side, and FIG. 28 showing an example in which the end partsof the inner plates are caused to protrude beyond the peripheral edgesof the outer plate, and a plurality of cut-out parts are formed in theprotruding parts and embedded by welding;

FIG. 29 is a perspective view of a bucket constituting prior art;

FIG. 30 is a sectional view along line 30-30 in. FIG. 29 prior towelding;

FIG. 31 is a sectional view along line 31-31 in FIG. 29 prior towelding;

FIGS. 32A and 32B are sectional views of essential parts in FIG. 29showing the welding process in the prior art, with FIG. 32A showing thestate following the first pass of welding, and

FIG. 32B showing the state following the second pass of welding;

FIG. 33 is a perspective view of a crusher constituting prior art;

FIG. 34 is a perspective view of a bucket in an example combining thethird and fourth embodiments;

FIG. 35 is a table showing the noise energy reduction rate of buckets inembodiments and examples of the present invention;

FIG. 36 is a side view of a bucket in an example that combines the firstthrough third embodiments; and

FIGS. 37A, 37B and 37C are side views showing examples in which themachine that is the object of vibration damping and the outer plate arecoupled so that the specified number of inner plates are tightly sealed.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention will be described belowwith reference to the attached figures. Furthermore, in the embodiments,mainly a construction machine such as a hydraulic excavator or the likecomprising work equipment that includes a bucket is envisioned.

A case in which the vibration occurring in the side plates of the bucketof a construction machine is suppressed, so that the noise emitted fromthese side plates is reduced, will be described as a first embodiment.FIG. 1 shows the side plate 11 of the bucket 10 that is the object ofvibration damping in the first embodiment, and FIG. 2 shows a sectionalview of the side plate 11. As is shown in FIG. 2, a plurality of thinsteel plates 21 are laminated on the side plate 11 of the bucket 10,thus forming laminated plate 20. Furthermore, relatively thick steelprotective plate 30 that protect the thin plates 21 are furthersuperimposed on the laminated plate 20, and the entire peripheries 20 aare fastened to the side plate 11 by fillet welding as indicated by thehatching shown in FIG. 1. The protective plate 30 is installed in orderto prevent the thin plates 21 from becoming worn by earth and sand orthe like. Furthermore, working in which protective plate 30 is notinstalled on the laminated plate 20 is also possible. Furthermore, inregard to the method that is used to fasten the peripheries (peripheraledges) of the laminated plate 20 to the side plate 11, besides a methodin which fastening is accomplished by all round fillet welding asdescribed above, fastening can also be accomplished by an arbitraryfastening method such as intermittent fillet welding, intermittent plugwelding, bolt fastening or the like. For example, these fasteningmethods are described in Japanese Patent Application Laid-Open No.2000-219168, U.S. Pat. No. 6,332,509 and Japanese Patent ApplicationLaid-Open No. 2002-48188.

The mechanism whereby the vibration generated in the side plate 11 issuppressed by the laminated plate 20 so that the noise emitted from sideplate 11 is reduced will be described with reference to FIGS. 4A and 4B.As is shown in FIG. 4B, when the side plate 11 vibrates, this vibrationis transmitted to the laminated plate 20, so that the thin plates 21,21′ that make up the laminated plate 20 undergo deformation. In thelaminated plate 20, in which numerous thin plates 21, 21′ aresuperimposed, the amount of deformation is different in each layer.Specifically, since the curvature radii r1 and r2 are different inadjacent thin plates 21, 21′, the displacement respectively varies asX+ΔX2, X+ΔX1 as a result of microscopic deformation caused by vibrationin the thin plates 21, 21′ in which the displacement was originally x(see FIG. 4A). As a result, a relative displacement of ΔX2−ΔX1 occursbetween the thin plates 21 and 21′. The relative displacement of ΔX2−ΔX1causes the generation of a frictional force (hereafter referred to asthe inter-layer frictional force) between the thin plates 21 and 21′.The vibrational energy that is generated in the side plate 11 isconverted into thermal energy by this frictional force. As a result, thevibration that is generated in the side plate 11 is suppressed, so thatthe noise that is emitted from the side plate 11 is reduced.

Accordingly, the independent deformation of the thin plates 21, 21′ asshown in FIG. 4B so that a relative displacement of ΔX2−ΔX1 is generatedis a condition for performing vibration damping. Conversely, if the thinplates 21, 21′ are fastened so that these plates act as an integralunit, independent deformation is impeded so that absolutely no relativedisplacement of ΔX2−ΔX1 is generated, or so that such a relativedisplacement is generated only to an extremely slight extent.Accordingly, no vibration damping effect is obtained, or only anextremely small vibration damping effect is obtained.

FIG. 3 shows the amount of deformation of the laminated plate 20corresponding to the loops and nodes of the vibration mode 1 in a casewhere the base material 11 is caused to vibrate in this vibration mode 1at a specified frequency. FIG. 5A shows the distribution of the size ofthe amplitude of the vibration in a case where the base material 11 iscaused to vibrate in the abovementioned vibration mode 1; here, therespective parts are indicated by different patterns corresponding tothe size of the amplitude. In FIG. 5A, the parts indicated by PH are theparts of loops where the amplitude is large, and the parts indicated byPL are the parts where the amplitude is 0, i. e., the parts of nodes.Thus, even in the case of the same structure, the size of the amplitudediffers according to the part; there are both parts where the amplitudeis large, i. e., parts that are loops of the vibration mode 1, and partswhere the amplitude is small, i. e., parts that are nodes of thevibration mode 1.

In the part E of loops where the amplitude is large, as is shown in FIG.3, the amount of deformation of the thin plates 21, 21′ that make up thelaminated plate 20 is large, and the inter-layer frictional force isalso large. Let us assume here that the laminated plate 20 is fastenedto the base material 11 in the part E constituting loops of thevibration mode 1. In this case, the independent deformation of thinplates 21, 21′ that make up the laminated plate 20 is impeded, so thatthe inter-layer frictional force is completely eliminated or isextremely small. Consequently, a vibration damping effect created by thelaminated plate 20 is not obtained, or else only an extremely slightvibration damping effect is obtained. Accordingly, in the firstembodiment, the part E that constitutes a loop of the vibration mode 1is avoided, and the laminated plate 20 is fastened to the base material11 in another part, i. e., in concrete terms, in the part G thatconstitutes a node of the vibration mode 1.

Meanwhile, when parts constituting nodes of the vibration mode 1 in theside plate 11 were checked, it was found that these parts were in theregion G shown in FIG. 1. The line connecting the circular arc center Cof the side plate 11 which has a substantially circular arc shape in oneportion of the lower side (one side) and the point A where there is atransition from the substantially circular arc shape to another shape onthe side where the bucket 10 is attached to the construction machine isdesignated as the line segment CA, the point where the line segment CAintersects with the laminated plate 20 is designated as B, and the lineconnecting the point B and the circular arc center C is designated asthe line segment BC. The region G consists of the center point d of theline segment BC and the part D in the vicinity of the center point d,the center point f of the line segment CA and the part F in the vicinityof the center point f, and the region between the part D and part F.

Accordingly, when the laminated plate 20 is fastened to the side plate11 of the bucket 10, the part D (for example) within the region G isfastened. FIG. 2 shows one example of the method used to fasten the partG of the laminated plate 20 to the side plate 11. As is shown in FIG. 2,a hole 50 is bored so that this hole passes through the protective plate30 and laminated plate 20 so as to reach the side plate 11, and plugwelding is performed so that the hole 50 is filled with a weldingmaterial 51. Furthermore, fastening may also be performed by arbitraryfastening means other than plug welding, such as bolt fastening or thelike.

The part G forming a node of the vibration mode 1 is inherently a partwhere the amount of deformation of the thin plates 21, 21′ forming thelaminated plate 20 is small or almost non-existent. Accordingly, even ifthis part is fastened, the vibration damping effect that is lost isextremely small or almost non-existent. Consequently, the deleteriouseffect on the vibration damping effect caused by the fastening of thelaminated plate 20 can be suppressed to a minimum. Thus, in the firstembodiment, since the construction is devised so that the optimal part Gin the interior part of the laminated plate 20 is fastened, there is noloss of the vibration damping effect due to thermal strain duringmanufacture or “floating” caused by external forces during use.Furthermore, the independent deformation of the thin plates 21 that makeup the laminated plate 20 is not impeded, so that a high vibrationdamping effect can be maintained. Moreover, in the first embodiment, apart other than the loop for a single vibration mode with a singlefrequency is fastened; however, a part other than a loop for respectivevibration modes at a plurality of frequencies may also be fastened.

FIGS. 5A through 5D respectively show the distributions of the size ofthe amplitude in cases where the side plate 11 was caused to vibrate invibration modes 1, 2, 3 and 4 with different frequencies. When the sideplate 11 was caused to vibrate in the vibration modes 1, 2, 3 and 4, theparts that were other than loops of the vibration nodes were in region Gfor all of the frequencies. As is shown in FIG. 1, this region Gconsists of the part D, part F and region between part D and part F.Accordingly, when the laminated plate 20 is fastened to the side plate11 of the bucket 10, if the part D within the region G is fastened, thedeleterious effect on the vibration damping effect caused by thefastening of the laminated plate 20 can be suppressed to a minimum.

Furthermore, in the first embodiment, the fastening parts in theinterior parts when the laminated plate 20 is fastened to the side plate11 are determined with the vibration mode being taken into account;however, the side plate 11 can also be fastened in parts other than theperipheral edges of the laminated plate 20. If this is done, thefloating and the like generated by the application of heat can beprevented. In particular, it is desirable that both parts (in theinterior parts) of the laminated plate 20 other than the peripheraledges, and the peripheral edge 20 a of the laminated plate 20, befastened to the side plate (or base material) 11. As a result, floatingand the like can be more securely prevented, and a high vibrationdamping effect can be maintained.

In the first embodiment, the side plate 11 of the bucket 10 of aconstruction machine constitute the object of vibration damping;however, the present invention can be applied in cases where anarbitrary base material is taken as the object of vibration damping.Specifically, the present invention may also be applied in cases wherebooms or arms other than buckets among the members constituting the workequipment of a construction machine are subjected to vibration damping.Furthermore, in the case of construction machines equipped with plates,the present invention may also be used to damp the vibration of theseplates. Furthermore, the present invention may also be applied tocrushers or the like equipped with hoppers, and used to damp thevibration of such hoppers, which constitute sources of noise. Moreover,the present invention may also be applied in cases where tracks, trackframes or the like constituting the running gear of constructionmachines are subjected to vibration damping.

Furthermore, vibration damping can also be performed by attachinglaminated plate 20 to components such as engines, hydraulic pumps or thelike. Especially in the case of hydraulic pumps, noise that is generatedas a result of the transmission of the pulsating motion generated by thehydraulic pump to piping is a problem. The frequencies that are aproblem in hydraulic pumps are the frequency of the pulsating motion ofthe pump and frequencies that are multiples of this pulsating motionfrequency. Accordingly, as in the first embodiment, if the system isdevised so that the distribution of the size of the amplitude isdetermined for respective vibration modes having the vibration frequencyand frequencies that are multiples of this vibration frequency, partsother than the loops of the respective vibration modes are specified,and these parts are fastened, noise caused by the pulsating motiongenerated by the hydraulic pump can be reduced.

Next, a case in which the vibration generated in the bucket of aconstruction machine is suppressed and noise emitted from the side plateand bottom plate is reduced will be described as a second embodiment.FIG. 6 is a perspective view of the bucket 10 that is the object ofvibration damping in the second embodiment, and FIG. 7 shows a sectionalview of the bucket 10. As is shown in FIG. 6, numerous thin steel platesare laminated to form laminated plate 20 on the side plate 11 of thebucket 10. The periphery 20 a of the laminated plate 20 is fastened tothe side plate 11 by all round fillet welding. Furthermore, in regard tothe method used to fasten the laminated plate 20 to the side plate 11,besides a method in which the plates are fastened by all round filletwelding as described above, it would also be possible to fasten theplates by an arbitrary fastening method such as intermittent filletwelding, intermittent plug welding, bolt fastening or the like.

Edge plate 13 is attached to the upper ends of the side plate 11, sothat the opening part of the bucket 10 is reinforced. A tooth 18 isattached to the bottom plate 12, and a bracket 19 is attached. An arm 41(shown in FIG. 11A) is attached to the bracket 19. Reinforcing members14 are attached to the corner parts where the side plate 11 and bottomplate 12 are connected on the inside of the bucket 10. The reinforcingmembers 14 are installed in order to maintain the strength of the bucket10 and increase the rigidity.

Bridge form connecting members 15 which connect the side plate 11 andbottom plate 12 are attached to a specified part K (see FIG. 10) of thecorner parts where the side plate 11 and bottom plate 12 are connectedon the inside of the bucket 10. The connecting members 15 are installedin order to reduce the noise emitted from the bottom plate 12 whilereinforcing the bottom plate 12 and maintaining the rigidity byconnecting the side plate 11 and bottom plate 12.

The standard for attaching connecting members 15 to the bottom plate 12will be described. FIG. 9 shows the ratio Wp/Hs of the width Wp of thebottom plate 12 to the height Hs of the side plate 11 on the horizontalaxis, and shows the respective noise contributions of the side plate 11and bottom plate 12 on the vertical axis. FIG. 9 shows the resultsobtained when the noise contributions were measured in a state in whichno laminated plate 20 or connecting member 15 was attached to the bucket10. The width Wp of the bottom plate 12 of the bucket 10 and the heightHs of the side plate 11 are defined as shown in FIG. 7.

As is shown in FIG. 9, in the region N in which the ratio Wp/Hs is lessthan 1.47, the noise contribution T2 of the bottom plate 12 is smallerthan the noise contribution T1 of the side plate 11. In other words,since the noise contribution T2 of the bottom plate 12 is smaller thanthe noise contribution T1 of the side plate 11, so that the noiseemitted from the side plate 11 is the dominant factor, the noise emittedfrom the bucket 10 can be reduced merely by attaching laminated plate 20to the side plate 11. Even if the bottom plate 12 is reinforced, thismakes almost no contribution to a reduction in the noise of the bucket10; consequently, there is no need to reinforce the bottom plate 12.Accordingly, in the case of buckets 10 in which the ratio Wp/Hs is lessthan 1.47, only laminated plate 20 is attached to the side plate 11, andthe attachment of connecting members 15 is omitted.

On the other hand, in the region Q in which the ratio Wp/Hs is 1.47 orgreater, the noise contribution T2 of the bottom plate 12 is equal to orgreater than the noise contribution T1 of the side plate 11. In otherwords, since the noise emitted from the bottom plate 12 is the dominantfactor, the mere attachment of laminated plate 20 to the side plate 11is insufficient, and the noise emitted from the bucket 10 cannot bereduced unless the noise emitted from the bottom plate 12 is reduced.Accordingly, in the case of buckets 10 in which the ratio Wp/Hs is 1.47or greater, connecting members 15 are attached to the corner parts 16where the side plate 11 and bottom plate 12 are connected (as shown inFIGS. 8A and 8B), in addition to the attachment of laminated plate 20 tothe side plate 11.

Thus, in the second embodiment, the standard for the requirement ofnoise countermeasures with respect to the bottom plate 12 is clearly setas the “ratio Wp/Hs of the width Wp of the bottom plate to the height Hsof the side plate being 1.47 or greater”, and the bottom plate 12 isreinforced according to this standard. As a result, noisecountermeasures can be taken with the minimum required effort for theminimum required buckets (among various types of buckets), withoutperforming noise experiments or the like. Accordingly, the cost of thedesign and manufacture of buckets can be greatly reduced. Furthermore,the question of whether or not the bottom plate 12 should be reinforcedcan be decided from the dimensions of respective parts in the designstage when buckets are newly designed, so that confirmation by noiseexperiments or the like is unnecessary. Accordingly, the process fromdesign to manufacture can be shortened.

Next, the attachment positions and attachment method of the connectingmembers 15 will be described in terms of respective examples.

Example 1

Connecting members 15 are attached over the entire region of the cornerparts 16.

Example 2

The main sources of the generation of the noise that is emitted from thebottom plate 12 are specified, and connecting members 15 are attached inthese parts only. When the frequency spectrum of the noise occurringduring actual work performed by the construction machine was analyzed,it was found that it is important to reduce noise in the frequency bandsin which large peaks are generated. Accordingly, vibration modalanalysis of the bucket 10 is performed at frequencies in the frequencybands in which large peaks are generated, and the main sources of thenoise that is emitted from the bottom plate 12 are located. FIG. 10shows a typical vibration mode amplitude distribution for the bucket 10;the respective parts are indicated by light or dark shades according tothe size of the amplitude. Furthermore, in FIG. 10, the attachmentpositions of the tooth 18 and bracket 19 are indicated in order toclarify the correspondence with FIG. 6.

As is shown in FIG. 10, the size of the amplitude differs according tothe part even if the structure is the same, so that there are partswhere the amplitude is large, i. e., parts that form loops of thevibration mode, and parts where the amplitude is small, i. e., partsthat form nodes of the vibration mode. It is conceivable that the partsthat form loops of the vibration mode in the corner parts 16 might bethe main sources of noise emitted from the bottom plate 12. Accordingly,the part K that forms the loop of the vibration mode in the corner parts16 are found from the amplitude distribution shown in FIG. 10, andconnecting members 15 are attached in the part K. In Example 2, thesystem is devised so that reinforcement is effected by attachingconnecting members 15 only in the part K that forms the loop of thevibration mode in the corner parts 16 where the side plate 11 and bottomplate 12 are connected; accordingly, reinforcement of the bottom plate12 is accomplished by the minimum necessary reinforcement, so that thedeleterious effect on the performance of the construction machine can bekept to a minimum.

Example 3

Connecting members 15 are attached in a configuration in which the ratioWp′/Hs of the substantial width Wp′ of the bottom plate 12 to the heightHs of the side plate 11 is smaller than 1.47. As is shown in FIGS. 8Aand 8B, connecting members 15 are respectively attached to both cornerparts 16 of the bottom plate 12, and the length of a line segment thatconnects the connection parts 12 a of the connecting members 15 isdesignated as the “substantial bottom plate width Wp′”. Here, as isshown in FIG. 9, it is assumed that the value of the ratio Wp/Hs priorto the attachment of the connecting members 15 is J2, and that this isin the region Q where the noise contribution T2 of the bottom plate 12is the dominant factor. Connecting members 15 are attached in the regionQ so that the reduction of the noise emitted from the bottom plate 12 ismost efficient in reducing the noise of the bucket 10.

If connecting members 15 are attached, the ratio Wp′/Hs can be alteredfrom a value of J2 to a value of J1, so that a transition can beeffected to the region N where the noise contribution T1 of the sideplate 11 is the dominant factor. The region N is a region where noiseemitted from the bottom plate 12 is not a problem, and noise emittedfrom the side plate 11 is a problem. The attachment of laminated plate20 to the side plate 11 in the region N is most efficient in reducingthe noise of the bucket 10.

Thus, in Example 3, the noise emitted from the bottom plate 12 can bereduced by attaching the connecting members 15 so that the ratio Wp′/Hsis less than 1.47. Since the noise emitted from the side plate 11 isreduced by attaching laminated plate 20 to the side plate 11 in a statein which the ratio Wp′/Hs is less than 1.47, the noise emitted from thebucket 10 can be most efficiently reduced to a maximal extent.

Example 4

Working that combines Example 2 and Example 3 is also possible.Specifically, part K that forms the loop of the vibration mode with thecorner parts 16 are found from the amplitude distribution in FIG. 10,and connecting members 15 are attached in the part K in a configurationin which the ratio Wp′/Hs is less than 1.47.

Example 5

In the abovementioned Examples 1 through 4, the corner parts 16 of thebottom plate 12 are reinforced using bridge form connecting members 15.However, it is sufficient if the corner parts 16 are reinforced asindicated by the broken lines in FIG. 8A; it is not absolutely necessaryto use bridge form connecting members 15. For example, working in whichthe corner parts 16 are filled with reinforcing members without leavinggaps is also possible. Furthermore, working in which a reinforcingmaterial is bonded to the outside of the bucket 10 rather than theinside of the bucket 10 (in the same manner as in the case ofconventional wear plate) is also possible.

Example 6

In the abovementioned Examples 1 through 5, a case in which buckets 10in which the ratio Wp/Hs is 1.47 or greater are reinforced isenvisioned. However, working in which reinforcing members such asconnecting members 15 or the like are attached in parts where the sideplate 11 and bottom plate 12 are connected on the inside of the bucket10, i. e., on the opposite side from the surfaces to which the laminatedplate 20 is attached, is also possible. In this case, the reinforcingmembers may be disposed over the entire region of the inside connectionparts of the side plate 11 and bottom plate 12, or may be disposed inonly some of the inside connection parts.

The effect of Example 6 will be described with reference to FIGS. 11Aand 11B. FIGS. 11A and 11B show how a bucket 10 is attached to the arm41 of a hydraulic excavator 40, and how this hydraulic excavator 40performs loading work into a truck 42. Here, a case is envisioned inwhich laminated plate 20 is attached to the bucket 10, but the bottomplate 12 is not reinforced by means of connecting members 15 or thelike. In this case, the noise emitted from the side plate 11 isconspicuously reduced by the laminated plate 20; however, the noiseemitted from the bottom plate remains large. Accordingly, a sufficientnoise reducing effect is not obtained with respect to noise from thefront S of the bucket 10.

On the other hand, a case may be envisioned in which laminated plate 20is attached to the bucket 10, and the bottom plate 12 is reinforced byconnecting members 15 or the like. In this case, the amplitude of thevibration that is a cause of noise is reduced as a result of the bottomplate 12 being reinforced by connecting members 15 or the like, so thatthe noise that is emitted from the bottom plate 12 is reduced.Accordingly, a sufficient noise reducing effect is obtained with respectto noise from the front S of the bucket 10. Furthermore, the noise fromthe bottom plate 12 also has an effect on the noise from the sides R ofthe bucket 10. Accordingly, noise can be sufficiently reduced in alldirections including the sides R of the bucket 10. Moreover, since onlythe inside connection parts of the bucket 10 are reinforced, theincrease in the weight of the reinforcing material is small compared toa case in which reinforcing members such as wear plates are installed onthe outside of the bucket 10.

Next, a third embodiment will be described with reference to FIGS. 12through 16C. As is shown in FIG. 12, in a bucket 101 which is a workingattachment of a hydraulic excavator, side plates 103, 103 arerespectively welded to the left and right sides of a bottom plate 102which is bent into a substantial C shape. Furthermore, edge plates 104,104 and 105 are respectively welded to the side plates 103, 103 andbottom plate 102, thus forming the opening part of the bucket 101. Theedge plates 104, 104 and 105 are members that are mounted in parts thatare subject to severe wear accompanying excavation work, and thethickness of these members is set at a thickness that is greater thanthat of the bottom plate 102 or side plate 103. A plurality of teeth 106are mounted on the edge plate 105. Pin bosses 107 that connect with thework equipment of the hydraulic excavator are installed on the outersurface of the end part of the bottom plate 102 on the opposite sidefrom the tooth attachment part. Wear plates 108 are disposed on theperipheral parts of the outside surfaces of the side plate 103 along thebottom plate 102.

As is also shown in FIG. 13, laminated plate 110 that has asubstantially semicircular shape is bonded so that this plate issurrounded by the edge plate 104 and wear plate 108. Holes 110 a usedfor plug welding are formed in the interior parts of the laminated plate110. As is shown in FIG. 14, the laminated plate 110 comprises innerplates 111 consisting of a specified number of laminated thin steelplates, and an outer plate 112 which is laminated on the outside of theinner plates 111. The outer plate 112 retains the inner plates 111, andhas a specified thickness that is used to protect the inner plates 111from wear and collision with rocks during excavation work.

The shape of the end portions on the substantially circular arc formsides of the respective inner plates 111 is a shape that substantiallymatches the inner circumferences of the wear plates 108, and rectangularcut-out parts 111 a with a specified width of w are formed in aplurality of locations including both ends (in the circumferentialdirection) of the end portions on the substantially circular arc formsides. A plurality of contact parts 111 b which contact the innercircumferences of the wear plates 108 are formed by being demarcated bythe cut-out parts 111 a. The depth of the cut-out parts 111 a is equalto the gap d1 between the outer plate 112 and the wear plate 108. Theshape of the end portions on the substantially circular arc form sidesof the outer plate 112 is a shape which is such that gaps d1 are formedas welding margins between these plates and the wear plates 108. Sincethe abovementioned shape is used, the laminated plate 110 is separatedby the formation of gap d1 with the wear plates 108 in the cut-out parts111 a as shown in FIG. 15A. In the contact part 111 b, as is shown inFIG. 15B, the inner plates 111 of the laminated plate 110 contact thewear plates 108, and the outer plate 112 are separated by the formationof gaps d1 with the wear plates 108. Specifically, the contact parts 111b protrude beyond the peripheral edges of the outer plate 112 by anamount equal to the gaps d1. The respective inner plates 111 and theouter plate 112 have shapes (substantially rectilinear shapes) which aresuch that gaps d2 (not shown in the figures, but similar to those shownin FIG. 31) are formed as welding margins between these plates and theedge plate 104.

The process whereby the laminated plate 110 is bonded to the sidesurfaces of the bucket 101 is as follows. First, a specified number ofinner plates 111 are superimposed, and these inner plates 111 arepositioned by causing the contact parts 111 b to contact the wear plates108. Next, the positioning of the outer plate 112 is performed utilizingthe cut-out parts 111 a of the inner plates 111. After the positioningof the laminated plate 110 (inner plates 111 and outer plate 112) iscompleted, the cut-out parts 111 a are attached and embedded by weldingas shown in FIG. 16A. As a result, the respective inner plates 111 areattached to the bucket 101 by intermittent welding. Next, the gaps d1between the cut-out parts 111 a and contact parts 111 b are embedded bycontinuous welding as shown in FIGS. 16B and 16C. Furthermore, the gapsd2 between the laminated plate 110 and edge plate 104 are embedded bycontinuous welding. Specifically, the laminated plate 110 is bonded tothe side surfaces of the bucket 101 by the intermittent welding of therespective inner plates 111 on the side of the wear plates 108, and bythe continuous welding of the outer plate 112. Preferably, furthermore,plug welding is performed in the holes 110 a, so that floating of therespective plates of the laminated plate 110 caused by thermal strain orthe like is prevented. As a result, the laminated plate 110 is bonded tothe side plate 103 so that the side plate 103, inner plates 111 andouter plate 112 adhere to each other in a substantially tight manner.

Next, the operation of the abovementioned construction will bedescribed. When the side plates 103 vibrate as a result of elasticdeformation, this vibration is transmitted via the welded parts, so thatthe respective inner plates 111 also vibrate due to elastic deformation,and a sliding motion occurs between the side plates 103 and inner plates111, and between the inner plates 111 and other inner plates 111, whilemicroscopic positional deviations and gaps are generated due to thepropagation delay and differences in rigidity. While the vibrationcontinues, such microscopic positional deviations and gaps continuallyarise while constantly varying; accordingly, friction and collisions arerepeated between these plates. Consequently, the vibrational energy ofthe side plates 103 is converted into thermal energy and dissipated bysuch friction and collisions. Accordingly, the vibration of the sideplates 103 can be reduced, and the noise that is emitted from the sideplates 103 can therefore also be reduced.

In other words, the respective plates vibrate in accordance with theconstraint conditions, so that microscopic relative displacements occurbetween the plates; accordingly, friction and collisions occur betweenthe plates. As a result of such friction and collisions, the vibrationalenergy is converted into thermal energy; accordingly, vibration thatcauses noise can be attenuated. In particular, if the plates adhere toeach other with a high degree of adhesion, friction between platesbecomes more prevalent than collisions caused by the generation of gapsbetween the plates, so that vibration can be attenuated with greaterefficiency.

Next, the effect of the present embodiment will be described. In thepresent embodiment, the entry of rain water into the interior parts ofthe laminated plate 110 is prevented by the continuous welding of theouter plate 112 of the laminated plate 110, so that the occurrence ofrusting between the plates is prevented, thus making it possible tomaintain the vibration damping performance. Since the edge plate 104 andwear plate 108 protect these continuously welded parts from friction andcollision with rocks or the like during excavation work, wear and damageof the welded parts of the laminated plate 110 can be prevented, so thatthe durability of the laminated plate 110 can be improved. Furthermore,since the welding is intermittent welding formed by the welding of theplurality of cut-out parts 111 a of the inner plates 111, the degree ofconstraint is low compared to continuous welding such as all roundwelding or the like; accordingly, superior vibration dampingcharacteristics are obtained, so that a vibration damping device with aconspicuous noise reducing effect can be obtained.

In regard to the effect from the standpoint of manufacture, thespecified number of inner plates 111 can be positioned merely by causingthe contact parts 111 b to abut against the wear plates 108; there is noneed to ensure a welding margin gap d1 with the wear plates 108. As aresult, the outer plate 112 can also easily be positioned utilizing thecut-out parts 111 a of the inner plates 111; accordingly, thepositioning work is easy, so that a low-cost vibration damping devicecan be obtained. Since the welding with the wear plates 108 is completedby intermittent welding based on the welding of the cut-out parts 111 aand the continuous welding of the outer peripheries of the outer plate112, the amount of welding required is small, so that the weldingprocess can be shortened, thus making it possible to obtain a low-costvibration damping device. In conventional techniques, a large number oftemporary attachments are performed in order to prevent the occurrenceof thermal strain. In the present invention, however, since the weldingof the cut-out parts 111 a also serves as a temporary attachment, thetemporary attachment process can be omitted, and since there is alsolittle continuous welding, the welded locations of the cut-out parts 111a that also serve as temporary attachments show at least littlegeneration of thermal strain.

Here, the results of a test confirming the relationship between thenoise reducing effect and the welding pitch of the inner plates 111 willbe described. Basically, the noise reducing effect of a vibrationdamping device using laminated plate increases as the number of pointsconstraining the laminated plate is reduced, i. e., as the length of thewelded parts becomes shorter. As will also be understood from theprevious description of the operation, the reason for this is thatrelative displacement between the layers is facilitated, so that alarger frictional force is generated. Accordingly, it would appear thata larger welding pitch of the inner plates 111 is desirable. However, ifthe welding pitch is excessively large, the conflicting problem of thegeneration of a knocking sound due to knocking between the inner platescaused by local vibration of the peripheral edges of the inner platesarises.

Accordingly, the relationship between the welding pitch of the innerplates and the generated noise level was measured. FIG. 17 shows themeasurement results. According to FIG. 17, the noise level graduallydrops as the welding pitch increases, with the generated noise showing aminimum value at a pitch of approximately 170 mm. It is seen that as thepitch increases beyond this value, the noise gradually increases as aresult of the abovementioned knocking sound, converging at asubstantially constant level at a pitch of approximately 280 mm Thisconvergent level is substantially equal to the noise level at a pitch of100 mm. Accordingly, if the pitch is set at a value smaller than 100 mm,the effect drops compared to a case where the pitch is greater than 170mm so that a knocking sound is generated. Furthermore, even in caseswhere it is desired to increase the welding pitch from the standpoint ofcost reduction, if the pitch is increased to a value exceeding 280 mm,the noise reduction effect drops as a result of the knocking sound. As aresult of the above, it is desirable to set the welding pitch of theinner plates at a value between 100 mm and 280 mm.

Accordingly, it is desirable to set the welding pitch of the innerplates 111 in the third embodiment, i. e., the length L1 of the contactparts 111 b in the circumferential direction, at a value between 100 mmand 280 mm. The length L1 of the contact parts 111 b in thecircumferential direction is defined as shown in FIG. 18.

In the third embodiment, a construction is used in which the peripheraledge portions of the inner plates 111 are intermittently welded bywelding cut-out parts 111 a disposed at specified intervals in theperipheral edges of the inner plates 111 to the side plate 103. However,the present invention is not limited to this; for instance, it wouldalso be possible to use other examples of laminated plate constructionsas shown in FIGS. 19A and 19B. Here, FIG. 19A is a perspective view ofanother example of a laminated plate, and FIG. 19B is a sectional viewalong line 19B-19B.

In FIGS. 19A and 19B, the construction has outer peripheral end partswith a substantially semicircular shape that is substantially equivalentto the inner circumferential shape of the wear plate 108 of the bucket101, and a plurality of inner plates 111A which do not have cut-outparts formed in the peripheral edges are laminated. An outer plate 112which has a diameter that is smaller than the diameter of the innerplates 111A by a specified dimension d1 is laminated on the outside ofthis plurality of laminated parts, thus forming a laminated plate 110A.The laminated plate 110A is bonded to the outside surface of the sideplate 103 of the bucket 101, so that the laminated plate 110A issurrounded by the edge plate 104 and wear plate 108. Only the outerplate 112 and the peripheral edges of the outermost inner plate 111A areconstrained by continuously welding the peripheral edges of the outerplate 112, the wear plate 108 and the edge plate 104. In this case aswell, not all of the plates are constrained; accordingly, the degree ofconstraint is low, so that superior vibration damping characteristicscan be obtained. Furthermore, the entry of rain water into the interiorparts of the laminated plate is prevented, so that the occurrence ofrusting between the plates is prevented, thus making it possible tomaintain the vibration damping characteristics over a long period oftime.

Next, a fourth embodiment will be described with reference to FIGS. 20through 23B. The fourth embodiment is an embodiment in which laminatedplate is applied to the hopper of a mobile crusher. In this mobilecrusher 120, as is shown in FIG. 20, a motive force device 123 ismounted on the rear part of a base 122 equipped with a track typepropulsion device 121, a crusher is mounted on the central part of thebase 122. Matter constituting the object of crushing which is placedinto a hopper 125 disposed on the front part of the base 122 (e. g.,rocks, concrete debris, wood, construction waste or the like) is crushedto a specified size by the crusher 124, and is fed out to the rear by afeed-out device which extends to the rear from the lower part of thebase 122.

As is shown in FIG. 21, a feeder 127 that conveys the inserted matterconstituting the object of crushing to the crusher 124 is disposed inthe central part of the hopper 125, and inclined wall surfaces 128, 128and 129 of the hopper 125 form an upward-oriented opening part so as tosurround the feeder 127. Laminated plates 130, 130 and 140 arerespectively bonded to the inclined wall surfaces 128, 128 and 129 ofthe hopper 125. The laminated plate 130, 130 and 140 have differentshapes but similar structures; accordingly, one of the laminated plate130 will be described below as an example.

As is shown in FIG. 22, this laminated plate 130 has an external shapethat is smaller than that of the inclined wall surface 128 all the wayaround, and is bonded to the central part of the inclined wall surface128. Holes 130 a used for plug welding are formed in specified parts ofthe laminated plate 130. The laminated plate 130 comprises inner plates131 consisting of a specified number of thin steel plates that arelaminated, and an outer plate 132 that is laminated on the outside ofthe inner plates 131. The outer plate 132 retains the inner plates 131,and has a specified thickness that acts to protect the inner plates 131from wear and collisions with the matter constituting the object ofcrushing at the time of insertion of this matter constituting the objectof crushing. The external shape of the outer plate 132 constitutes theexternal shape of the laminated plate 130, and comprises a plurality ofprotruding parts 131 a on the peripheral edges of the inner plates 131that match the peripheral edge shape of the outer plate 132, and aplurality of cut-out parts 131 b that are indented with respect to theperipheral edge shape of the outer plate 132.

The process whereby the laminated plate 130 is bonded to the inclinedwall surface 128 of the hopper 125 is as follows. First, on a work bench(not shown in the figures) on which a jig (not shown in the figures)that contacts two adjacent sides of the laminated plate 130 is set, aspecified number of inner plates 131 are superimposed, and an outerplate 132 is superimposed on top of these plates; then, positioning isperformed by causing all of the plates to contact the jig, and temporarywelding is performed in several locations on the peripheral edges. Next,the temporarily welded laminated plate 130 is disposed in a specifiedpart on the inclined wall surface 128, and the laminated plate 130 isconnected to the inclined wall surface 128 by continuous welding (allround welding). As a result, while the outer plate 132 is continuouslywelded, the respective inner plates 131 are subjected to intermittentwelding in which these inner plates 131 are not welded in the cut-outparts 131 b, and are welded to the inclined wall surface 128 only in theplurality of protruding parts 131 a, as shown in FIGS. 23A and 23B.

According to the measurement data shown in FIG. 17, it is desirable toset the spacing between the protruding parts 131 a of the inner plates131 in the fourth embodiment, i. e., the length L2 of the cut-out parts131 b in the circumferential direction, in the range of 100 mm to 280mm. The length L2 of the cut-out parts 131 b in the circumferentialdirection is defined as shown in FIG. 24.

Since the action of noise reduction by means of the laminated plate 130is similar to that in the third embodiment, a description of this actionwill be omitted here. Next, the effect of the fourth embodiment will bedescribed. In the present embodiment, the entry of rain water into theinterior parts of the laminated plate 130 is prevented by the continuouswelding of the outer plate 132 of the laminated plate 130, so that theoccurrence of rusting between the plates can be prevented, thus makingit possible to maintain the vibration damping performance. Since theinner plates 131 are intermittently welded so that the degree ofconstraint is lower than in the case of continuous welding (all roundwelding), superior vibration damping characteristics are obtained, sothat a vibration damping device which has a conspicuous noise reducingeffect is obtained. In regard to the effect from the standpoint ofmanufacture, since intermediate welding can be accomplished by weldingthe protruding parts 131 a of the inner plates 131 by a continuouswelding process performed on the outer plate 132, the manufacturingprocess can be simplified and the cost can be reduced. Furthermore,since the protruding parts 131 a of the specified number of inner plates131 match the external shape of the outer plate 132, the positioning ofthe respective inner plates 131 and the outer plate 132 is facilitated,so that a low-cost vibration damping device can be obtained.

Furthermore, the present invention is not limited to the third andfourth embodiments; alterations and modifications may be performedwithin the scope of the present invention. For instance, an example inwhich the inner plates 111 were constrained by intermittent welding infive places on the side of the wear plate 108 (i. e., the cut-out parts111 a) was described; however, such constraints may be appropriatelyselected in accordance with the required strength and the frequency bandof the noise for which a reduction is desired.

An example was described in which rectangular cut-out parts 111 a wereformed in the inner plates; however, the shape of the cut-out parts isnot limited to rectangular; wave-form cut-out parts 111 c may also beformed as shown in FIG. 25A. Similarly, the cut-out parts 131 b in theinner plates 131 of the fourth embodiment may also be formed aswave-form cut-out parts. In cases where the inner plates 111 aremanufactured by means of a turret punching press or the like, gaps aregenerated between the respective inner plates 111 by the changes thatoccur in the end parts, so that the vibration damping performance drops;ordinarily, therefore, the inner plates 111 are manufactured by laserworking. Accordingly, manufacture is not impeded even if the cut-outshape is a wave-form shape; furthermore, in cases where a large numberof sites of intermediate welding are required as a result of strengthrequirements, a wave-form shape makes it possible to shorten thelaser-cut length to a greater extent than a rectangular shape does, sothat the productivity is improved.

Instead of forming rectangular cut-out parts 111 a in the inner plates111, it would also be possible to construct the device so that holes 111d used for plug welding are formed in the peripheral edges of the innerplates 111 on the side of the wear-resistant parts 108, and therespective inner plates 111 are constrained to the side plate 103 byplug welding as shown in FIG. 25B. The peripheral edges of the innerplates 111 are intermittently welded by the plug welding performed inthe holes 111 d. The construction may also be devised so that constraintlocations are not provided on the inner plates 111 alone, but aplurality of holes 110 a used for plug welding that welds the innerplates 111 to the side plate together with the outer plate 112 areinstead provided as shown in FIG. 25C. The inner plates 111 and outerplate 112 are intermittently welded by the plug welding performed in theholes 110 a, so that an effect similar to that of the abovementionedembodiments is obtained.

In the laminated plate 110, an example is shown in which continuouswelding is performed in the gaps d2 between the laminated plate 110 andthe edge plate 104; however, in these parts as well, it would also bepossible to constrain the parts by intermittent welding of the innerplates 111. Specifically, a construction can be used in which the endparts of the inner plates 111 on the side of the edge plate 104 arecaused to protrude beyond the peripheral edges of the outer plate 112,cut-out parts 111 a are formed in these protruding parts, andintermittent welding is accomplished by means of welding that embeds thecut-out parts 111 a. If this is used, the number of locations where theinner plates 111 are constrained is reduced; accordingly, a vibrationdamping device with an even more superior vibration damping performancecan be obtained.

The technique of the fourth embodiment can also be added to the thirdembodiment. Specifically, as is shown in FIG. 27, a plurality ofprotruding parts 111 e that match the external shape of the outer plate112, and a plurality of cut-out parts 111 f that are indented withrespect to the external shape of the outer plate 112, are formed in theend parts of the inner plates 111 on the side of the edge plate 104. Asa result, even if continuous welding is performed on the end parts ofthe laminated plate 110 on the side of the edge plate 104, this resultsin intermittent welding of the inner plates 111 in which only theprotruding parts 111 e are welded. As a result, the number of locationswhere the inner plates 111 are constrained is reduced, so that avibration damping device with an even more superior vibration dampingperformance can be obtained.

Furthermore, the technique of the third embodiment can also be added tothe fourth embodiment. Specifically, as is shown in FIG. 28,substantially L-shaped wear plate 138 that can contact two adjacentsides of the laminated plate 130 are attached to the inclined wallsurfaces 128, the end parts of the inner plates 131 facing the wearplate 138 are caused to protrude beyond the peripheral edges of theouter plate 132 so as to contact the wear plate 138, and a plurality ofcut-out parts 131 c are formed in these protruding parts. A plurality ofcontact parts 131 d that contact the wear plate 138 as a result of beingdemarcated by the cut-out parts 131 c are formed on the protrudingparts. After intermittent welding is accomplished by embedding thisplurality of cut-out parts 131 c by welding, the outer plate 132 arecontinuously welded so that the laminated plate 130 is bonded to theinclined wall surfaces 128. As a result, the respective inner plates 131can be positioned on the inclined wall surfaces 128 by causing theseplates to abut against the wear plate 138. Since the wear plate 138protects the welded parts on the side of the wear plate 138 from wear orcollision with the inserted matter that is the object of crushing, wearand damage of the welded parts of the laminated plate 130 can beprevented, so that the durability of the laminated plate 130 can beimproved.

In the abovementioned third and fourth embodiments, a description waspresented using a construction example in which the thickness of thelaminated plate 110, 130, i. e., the total laminated height of the innerplates and outer plates, was set at substantially the same height as theheight of the wear plates 108, 138. However, it is desirable to set thetotal laminated height at a height that is equal to or less than theheight of the wear plates 108, 138; in such a case, wear or damage ofthe welded parts of the laminated plate can be more securely preventedby the wear plates. The bucket 101 of a hydraulic excavator (includingrespective constituent members such as the side plate 3 or the like) andthe hopper 125 of a mobile crusher (including respective constituentmembers such as the inclined wall surfaces 128 or the like) were citedas examples of machine members to which the laminated plate was bonded.However, the laminated plate can be applied to arbitrary machine membersfor which a reduction in noise is desired, and it goes without sayingthat such laminated plate can also be applied to buckets of wheelloaders or hoppers of fixed crushing equipment. As was described above,invasion by rain water can be prevented by continuously welding theouter plate of the laminated plate so that the occurrence of rustingbetween plates can be prevented, and the degree of constraint of theinner plates of the laminated plate can be kept low by intermittentlywelding these inner plates; accordingly, superior vibration dampingcharacteristics can be obtained so that a vibration damping device thathas a conspicuous noise reducing effect can be obtained.

An example in which the first embodiment and second embodiment arecombined is also possible. Specifically, as is shown in FIG. 34, thebucket 200 is devised in the same manner as in the first embodiment sothat laminated plate 220 is attached to the side plate 211 by all roundfillet welding 230, and the interior parts of the laminated plate 220and the side plate 211 are welded by plug welding 250 in partscorresponding to the part D shown in FIG. 1 (optimization of plugwelding). Furthermore, in the bucket 200, bridge form connecting members215 that connect the side plate 211 and bottom plate 212 are attached inspecified part K (see FIG. 10) among the corner parts where the sideplate 211 and bottom plate 212 are connected (in the same manner as inthe second embodiment). The relationship between the width Wp of thebottom plate 212 and the height Hs of the side plate 211 in thisembodiment is in the region Q shown in FIG. 9 (i. e., the ratio Wp/Hs is1.47 or greater). Moreover, in FIG. 34, reinforcing members 214 arefastened to the corner parts where the side plate 211 and bottom plate212 are connected; however, the use of reinforcing members 214 may beomitted.

The noise energy reduction rate obtained using such a combinationexample will be described with reference to FIG. 35. Here, the noiseenergy reduction rate Ed is determined by experimentally measuring thenoise energy generated before and after the attachment of laminatedplate 220 and/or connecting members 215, and calculating this noiseenergy reduction rate as Ed=[(noise energy E1 generated prior toattachment−noise energy E2 generated after attachment)/E1]×100(%). Theside plate contribution and the bottom plate contribution indicate therates in the reduction of the noise respectively emitted from the sideplate and bottom plate. “OVERALL” in FIG. 35 indicates the valueobtained by totaling the respective reduction rates of the side plateand bottom plate after multiplying these rates by the contributionrates. In the bucket 200 of the present example prior to the attachmentof laminated plate 220 or the like, the side plate contribution rate is39%, and the bottom plate contribution rate is 61%; accordingly, this isa case where the contribution of the noise emitted from the bottom plate212 is larger.

In FIG. 35, the noise energy reduction rate Ed is also measured forseveral constructions other than the present embodiment; the constituentelements of the bucket corresponding to the respective item Nos. are asfollows. Here, the bucket constituting the base is a bucket prior to theattachment of noise reducing members such as laminated plate 220,connecting members 215 or the like.

Item 1: all round fillet welding 230 of the laminated plate 220, andplug welding (not shown in the figures) in the parts of “loops” of thevibration mode.

Item 2: all round fillet welding 230 of the laminated plate 220, andplug welding 250 in parts corresponding to the part D.

Item 3: manufacture (no plug welding) so that “floating” is notgenerated in the laminated plate 220, with the fact that themanufacturing cost is extremely high when all round fillet welding 230of the laminated plate 220 to the side plate 211 being ignored.

Item 4: connecting members 215 are attached in the part K (no laminatedplate).

Item 5: combined use of item 2 and item 4.

Item 6: respective noise energy reduction rates of item 2 and item 4 areadded arithmetically.

Item 7: item 1 and item 4 are used in combination.

The noise energy reduction rates in the buckets with the abovementionedrespective items will be described in comparative terms. Item 3 is theideal attachment state of the laminated plate 220; however, thisinvolves an extremely high manufacturing cost, and there are alsoproblems in terms of the occurrence of floating caused by collisionsduring the use of the bucket, so that this item is not suitable forpractical use. On the other hand, in the case of item 2 which uses thefirst embodiment, it is seen that a reduction rate that is substantiallyclose to that of the ideal attachment state can be achieved. Moreover,in the case of item 1 which differs from Embodiment 1, in addition tothe fact that the reduction rate is low, no effect on the bottom plate212 is obtained, either. It appears that this is due to the fact thatthe vibrational energy cannot be sufficiently dissipated because of theinsufficiency of the attenuating effect. Item 4 is an example that wasworked in order to investigate the effect of the connecting members 215alone; in this case, the reduction rate of the side plate contributionwas 7%. It is inferred that this is due to the fact that the vibrationamplitude of the peripheral edge parts of the side plate 211 is reducedby the connecting members 215, which also serve to reinforce the bottomplate 212. Thus, the reason that noise is reduced by the reinforcementof the bottom plate 212 is that the rigidity Y of the bucket 200 isincreased, and the reason that noise is reduced by the laminated plate220 is that the damping ratio ζ of the bucket 200 is increased. It isknown that the vibrational energy Ev within a fixed period of time isproportional to “1/{2Yζ×(1−ζ²)^(1/2)}”, and if an improvement inrigidity and an improvement in damping characteristics aresimultaneously achieved, an effect that is greater than that obtained bysimple addition is achieved.

Item 5 is a case in which the first embodiment (item 2) and secondembodiment (item 4) are both used together (i. e., the example of FIG.34). In cases where the second item and fourth item are usedindependently, the reduction rates are merely added to produce item 6.Accordingly, in item 5, an effect that is greater than additive isobtained as a result of a synergistic effect. Furthermore, in caseswhere plug welding is performed in the loops (item 1), the laminatedplate has no effect on the bottom plate; accordingly, even if connectingmembers are attached, the effect is reduced (item 7).

In the present example (FIG. 34), a case was described in which theratio Wp/Hs of the width Wp of the bottom plate 212 to height Hs of theside plate 211 was 1.47 or greater. However, it is also useful even ifthe ratio Wp/Hs is less than 1.47. Specifically, a noise energy reducingeffect can also be obtained in cases where the noise energy of the sideplate 211 (where the contribution rate is large depending on thelaminated plate 220) drops sufficiently and the contribution of thebottom plate 212 is relatively high.

Furthermore, an example combining the first through third embodiments isalso possible. Specifically, the bucket 300 of the present example shownin FIG. 36, in contrast to the example shown in FIG. 34, is devised sothat i) the laminated plate 320 comprises inner plates 311 that havecut-out parts 311 a and contact parts 311 b, and outer plate 312, likethe laminated plate comprising inner plates 111 that have cut-out parts111 a and contact parts 111 b and outer plate 112 in FIG. 13, and ii)the inner plates 311 are intermittently welded and the outer plate 312is welded by all round fillet welding as in the third embodiment.

The noise energy reduction rate Ed is also measured in the case ofconstructions other than this example; this will be described withreference to FIG. 35. The bucket construction elements are as describedin items 8 through 12; as was described above, the bucket thatconstitutes the base is a bucket prior to the attachment of noisereducing members.

Item 8: as in the third embodiment, the inner plates 311 of thelaminated plate 320 are intermittently welded, and the outer plate 312is welded by all round fillet welding; here, during welding, the factthat the manufacturing cost is extremely high is ignored, andmanufacture is performed (without plug welding) so that “floating” doesnot occur in the laminated plate 320.

Item 9: as in the third embodiment, the inner plates 311 of thelaminated plate 320 are intermittently welded, and the outer plate 312is welded by all round fillet welding; furthermore, plug welding (notshown in the figures) is performed in the parts of the “loops” of thevibration mode.

Item 10: as in the third embodiment, the inner plates 311 of thelaminated plate 320 are intermittently welded, and the outer plate 312is welded by all round fillet welding; furthermore, item 2 is also usedin combination.

Item 11: Item 10 and item 4 are used in combination.

Item 12: additive addition of the respective noise energy reductionrates of item 10 and item 4.

The noise energy reduction rates in buckets with the abovementioneditems 8 through 12 will be described in a comparative description. Item8 is similar to item 3; although the reduction rate is high, the degreeof practicality is low because of problems of manufacturing cost andfloating. In the case of item 9, plug welding is performed in the loops,so that the reduction rate is greatly reduced. In the case of item 10,in which plug welding 250 is performed in the part D as in Embodiment 1(in contrast to item 9), the positions of plug welding are optimized, sothat there is no lowering of the reduction rate, and a practicalstructure is obtained. In the case of item 11 (i. e., the presentembodiment shown in FIG. 36), compared to item 10, connecting members215 are further attached as in the second embodiment, so that anextremely large reduction rate is obtained. In the case of item 11, asis clear from a comparison with item 12, an effect that is greater thana simple additive effect is obtained as a result of a synergisticeffect.

In the abovementioned third embodiment and fourth embodiment, aplurality of cut-out parts 111 a and a plurality of protruding parts 131a are formed in the inner plates 111, 131 of the laminated plates 110,130, and the inner plates 111, 131 are intermittently welded by weldingthe plurality of cut-out parts 111 a or plurality of protruding parts131 a to the side plates 103 of the bucket 101 or inclined wall surfaces128 of the hopper 125 constituting the machine that is the object ofvibration damping.

However, it would also be possible to connect the laminated plates tothe machine that is the object of vibration damping by continuouslywelding only the outer plates, without intermittently welding the innerplates, so that the inner plates are tightly sealed by the outer platesand the machine that is the object of vibration damping.

Specifically, the laminated plate 910 shown in FIG. 37A consists of aspecified number of inner plates 912 that are laminated on the machine901 that is the object of vibration damping, and an outer plate 911which is further laminated on the outside of this specified number ofinner plates 912, and which has an area that is larger than that of theinner plates 912. The machine 901 that is the object of vibrationdamping and the outer plate 911 are welded by all round welding (thearea of all round welding is indicated by 913) in a state in which thespecified number of inner plates 912 are clamped by the machine 901 thatis the object of vibration damping and the outer plate 911. As a result,the machine 901 that is the object of vibration damping and the outerplate 911 are connected so that the specified number of inner plates 912are tightly sealed.

In this example, there are no welded parts on the specified number ofinner plates 912 that constrain the deformation of the inner plates.912, and the all round welding prevents the occurrence of rusting due toinvasion by rain water; accordingly, a favorable vibration dampingperformance is obtained.

In FIG. 37A, the outer plate 911 is directly connected to the machine901 that is the object of vibration damping; however, it would also bepossible to connect the outer plate 911 to the machine 901 that is theobject of vibration damping with a connecting member interposed.

Specifically, as in the case of FIG. 37A, the laminated plate 910 shownin FIG. 37B consists of a specified number of inner plates 912 that arelaminated on the machine 901 that is the object of vibration damping,and an outer plate 911 which is further laminated on the outside of thespecified number of inner plates 912, and which has an area that islarger than that of the inner plates 912. As a result, the specifiednumber of inner plates 912 are clamped by the machine 901 that is theobject of vibration damping and the outer plate 911. Furthermore, aconnecting member 914 is disposed on the entire periphery of the outerplate 911. Moreover, the outer plate 911 and the connecting member 914are connected by all round welding (the area of all round welding isindicated by 916), and the connecting member 914 and the machine 901that is the object of vibration damping are further connected by allround welding (the area of this all round welding is indicated by 915).As a result, the machine 901 that is the object of vibration damping andthe outer plate 911 are connected via the connecting member 914 so thatthe specified number of inner plates 912 are tightly sealed.

In this example, there are no welded parts on the specified number ofinner plates 912 that constrain the deformation of the inner plates 912,and the all round welding prevents the occurrence of rusting due toinvasion by rain water; accordingly, a favorable vibration dampingperformance is obtained.

Furthermore, for example, if the construction is devised so that thespecified number of inner plates 912 and the outer plate 911 areconnected beforehand by plug welding (the area of plug welding isindicated by 917), and the connecting members 915 are then welded, thepositioning of the laminated plate 910 on the machine 901 that is theobject of vibration damping can easily be accomplished, so that themanufacturing cost can be lowered. Furthermore, floating of thelaminated plate 910 can be prevented by such plug welding.

Furthermore, working in which the connecting members are used as jigsfor the positioning of the laminated plate is also possible.

Specifically, the laminated plate shown in FIG. 37C consists of aspecified number of inner plates 912 that are laminated on the machine901 that is the object of vibration damping, and an outer plate 911which is further laminated on the outside of this specified number ofinner plates 912, and which has the same area and same shape as theinner plates 912. As a result, the specified number of inner plates 912are clamped by the machine 901 that is the object of vibration dampingand the outer plate 911. Furthermore, a connecting member 918 isdisposed on the entire periphery of the outer plate 911. The laminatedplate 910 is positioned by causing the specified number of inner plates912 and the outer plate 911 to contact the inner wall of the connectingmember 918. Furthermore, the outer plate 911 and connecting member 918are connected by all round welding (the area of all round welding isindicated by 920), and the connecting member 918 and the machine 901that is the object of vibration damping are further connected by allround welding (the area of this all round welding is indicated by 919).As a result, the machine 901 that is the object of vibration damping andthe outer plate 911 are connected via the connecting member 918 so thatthe specified number of inner plates 912 are tightly sealed.

In this example, there are no welded parts on the specified number ofinner plates 912 that constrain the deformation of the inner plates 912,and the all round welding prevents the occurrence of rusting due toinvasion by rain water; accordingly, a favorable vibration dampingperformance is obtained.

Furthermore, the positioning of the laminated plate 910 on the machine901 that is the object of vibration damping can easily be accomplishedusing the connecting members 918, so that the manufacturing cost can befurther reduced.

Moreover, in FIGS. 37A, 37B and 37C, connection is accomplished bywelding; however, working using an adhesive agent or sealing materialinstead of welding is also possible.

Furthermore, as was described in the third embodiment and fourthembodiment, the machine 901 that is the object of vibration damping inFIGS. 37A, 37B and 37C is, for example, the side plate 103 of a bucket101, the inclined wall surface 128 of a hopper 125 or the like.

Furthermore, working may also be performed by appropriately combiningthe laminated plate 910 in FIGS. 37A, 37B and 37C with the workingconfigurations described in the first embodiment, second embodiment,third embodiment or fourth embodiment.

INDUSTRIAL APPLICABILITY

The present invention is useful as a vibration damping device and bucketof a construction machine in which the vibration generated in a basematerial, side plate or the like is suppressed, so that the noiseemitted from the base material or the like is reduced.

1. A bucket for a construction machine comprising: a side plate (11); abottom plate (12), at least a portion of which is connected to the sideplate (11); and a laminated plate (20) which is attached to the sideplate (11); wherein in cases where a ratio Wp/Hs of a width Wp of thebottom plate (12) to a height Hs of the side plate (11) is 1.47 orgreater, at least a part (16) of the portion where the side plate (11)and the bottom plate (12) are connected is reinforced.
 2. A bucket for aconstruction machine comprising: a side plate (11); a bottom plate (12),at least a portion of which is connected to the side plate (11); and alaminated plate (20) which is attached to the side plate (11); whereinin cases where a ratio Wp/Hs of a width Wp of the bottom plate (12) to aheight Hs of the side plate (11) is 1.47 or greater, a part (K), whichforms a loop of a vibration mode, of the portion where the side plate(11) and the bottom plate (12) are connected is reinforced.
 3. A bucketfor a construction machine comprising: a side plate (11); a bottom plate(12), at least a portion of which is connected to the side plate (11);and a laminated plate (20) which is attached to the side plate (11);wherein in cases where a ratio Wp/Hs of a width Wp of the bottom plate(12) to a height Hs of the side plate (11) is 1.47 or greater, aconnecting member (15) that connects the side plate (11) and the bottomplate (12) is provided so that a ratio Wp/Hs of a substantial width Wpof the bottom plate (12) to the height Hs is less than 1.47.
 4. A bucketfor a construction machine comprising: a side plate (11); a bottom plate(12), at least a portion of which is connected to the side plate (11);and a laminated plate (20) which is attached to an outside of the sideplate (11); wherein at least a part (16) of the portion where the sideplate (11) and the bottom plate (12) are connected on insides of theside plate (11) and the bottom plate (12) is reinforced.
 5. The bucketfor a construction machine according to claim 4, wherein the laminatedplate (910) is formed by laminating a specified number of inner plates(912) and an outer plate (911) that is disposed on an outside of thespecified number of the inner plates (912), and the specified number ofthe inner plates (912) are tightly sealed by the outer plate (911) andthe side plate (211).